One goal of current relativistic heavy ion collision experiments is to map the QCD phase diagram as a function of temperature \(T\)  and baryon chemical potential \(\mu _{\rm B}\) . The phase transition from hadron phase to quark-gluon plasma (QGP) is first order at low \(T\)  and high \(\mu _{\rm B}\) . The first order phase transition line ends at a critical point at which the transition is second order. At high \(T\)  and small \(\mu _{\rm B}\) , the hadron phase smoothly transitions to QGP phase [1]}, [2]}, [3]}, [4]}.
